Fuel and related compositions – Liquid fuels – Containing organic -c
Reexamination Certificate
2000-01-19
2002-10-01
Toomer, Cephia D. (Department: 1714)
Fuel and related compositions
Liquid fuels
Containing organic -c
C044S397000, C526S320000, C526S321000, C526S322000, C526S323000, C526S324000
Reexamination Certificate
active
06458174
ABSTRACT:
FIELD OF THE INVENTION
The present invention is described in the German priority application No. 199 01 803.0 filed Jan. 19, 1999.
DESCRIPTION OF THE RELATED ART
The present invention relates to copolymers containing structural units of olefins, modified maleic anhydride and polyolefins, and to their use as additives to fuel oils for improving their cold-flow properties.
Crude oils and middle distillates obtained by distillation of crude oils, such as gas oil, diesel oil or heating oil, contain, depending on the origin of the crude oils, various amounts of n-paraffins, which, when the temperature is reduced, crystallize out as platelet-shaped crystals and in some cases agglomerate with inclusion of oil. This results in an impairment in the flow properties of these oils or distillates, which can result, for example, in problems during recovery, transport, storage and/or use of the mineral oils and mineral oil distillates. In the case of mineral oils, this crystallization phenomenon can result in deposits on the pipe walls during transport through pipelines, especially in winter, and in individual cases, for example during shut-down of a pipeline, can even result in complete blockage thereof. Precipitation of paraffins can also cause difficulties during storage and further processing of mineral oils. Thus, it may under certain circumstances be necessary to store the mineral oils in heated tanks in winter. In the case of mineral oil distillates, crystallization can result in blockage of the filters in diesel engines and furnaces, preventing reliable metering of the fuel oils and possibly resulting in total interruption of the fuel or heating medium supply. Besides the classical methods of removing crystallized-out paraffins (thermal, mechanical or using solvents), which merely relate to the removal of precipitations which have already occurred, recent years have seen the development of chemical additives (so-called flow improvers or paraffin inhibitors), which, through physical interaction with the precipitating paraffin crystals, result in their shape, size and adhesion properties being modified. The additives act here as additional crystal nuclei and partially crystallize out with the paraffins, resulting in a relatively large number of relatively small paraffin crystals having a modified crystal shape. Part of the action of the additives is also explained by dispersion of the paraffin crystals. The modified paraffin crystals have a lower tendency toward agglomeration, and consequently the oils to which these additives have been added can still be pumped and processed at temperatures which are frequently more than 20° lower than in the case of oils to which no additives have been added.
The flow and low-temperature behavior of mineral oils and mineral oil distillates is described, inter alia, by indicating the cloud point (determined in accordance with ISO 3015), the pour point (determined in accordance with ISO 3016) and the cold filter plugging point (CFPP; determined in accordance with EN 116). These parameters are measured in ° C.
Typical flow improvers for crude oils and middle distillates are copolymers of ethylene with carboxylic esters of vinyl alcohol. Thus, according to DE-A-11 47 799, oil-soluble copolymers of ethylene and vinyl acetate having a molecular weight of from about 1000 to 3000 are added to petroleum distillate fuels having a boiling point of from about 120 to 400° C. Preference is given to copolymers containing from about 60 to 99% by weight of ethylene and from about 1 to 40% by weight of vinyl acetate. They are particularly effective if they have been prepared by free-radical polymerization in an inert solvent at temperatures of from about 70 to 130° C. and pressures of from 35 to 2100 atmospheres above atmospheric pressure (DE-A-19 14 756).
The prior art furthermore discloses so-called comb polymers, which are derived from ethylenically unsaturated monomers having relatively long (for example C
8
-C
30
), preferably linear, alkyl radicals. These are employed in particular in relatively high-boiling, paraffin-rich mineral oils, if desired in combination with ethylene copolymers, for improving the cold-flow properties (for example GB-A-1,469,016 and EP-A-0 214 786). According to EP-A-0 153 176, comb polymers containing C
12
-C
14
-alkyl radicals are also employed in narrow-cut distillates having, for example, 90-20% distillation ranges <100° C. and final boiling points of about 340-370° C. According to U.S. Pat. No. 2,542,542 and GB-A-1,468,588, copolymers of maleic anhydride (MA) and &agr;-olefins which have been esterified by means of long-chain fatty alcohols are employed for treating crude oils.
EP-A-0 719 290 discloses a copolymer of a monoethylenically unsaturated carboxylic acid having 4 to 6 carbon atoms, an oligomer of propene or a branched &agr;-olefin having 4 to 10 carbon atoms and a further monoethylenically unsaturated compound which is copolymerizable with said compounds. Reaction thereof with an amine gives oil-soluble reaction products which are suitable as additives for lubricant oils and motor fuels. The document does not disclose any composition comprising a maleic ester, a polyolefin and an &agr;-olefin.
WO-90/03359 discloses copolymers of polyolefins having more than 32 carbon atoms and olefinically unsaturated carboxylic acids or derivatives. However, the esters mentioned in the documents are not specified.
DE-A-2 050 071 discloses copolymers of an ethylenically unsaturated dicarboxylic acid or derivatives thereof with an &agr;-olefin having at least 20 carbon atoms which have been esterified by means of fatty alcohols. However, the document does not disclose, for example, any polyolefins as comonomers for the copolymers.
According to, for example, DE-A-2 050 071 and EP-A-214 786, the preferred process for the preparation of the copolymers is solvent-free bulk polymerization of MA and &agr;-olefins, giving high-molecular-weight copolymers, followed by esterification. However, the copolymers of MA and &agr;-olefins as intermediate for the additives prepared therefrom by esterification using fatty alcohols have increased rigidity owing to their high molecular weights. It is evident from such high viscosities and solidification points that the polymers can only be handled at elevated temperatures. For this reason, their processing, formulation and storage must take place at elevated temperature, or a solution of them in a suitable solvent must be prepared immediately after their preparation process.
The object of the present invention was thus to find an effective cold-flow improver for mineral oils (crude oils and middle distillates) based on esterified dicarboxylic acids and linear &agr;-olefins which is nevertheless processable at lower temperatures.
SUMMARY OF THE INVENTION
Surprisingly, it has been found that incorporation of certain amounts of branched polyolefins does not impair the effectiveness of the esters as cold-flow improvers, but significantly simplifies handling of the solvent-free terpolymers carrying anhydride groups. Furthermore, the solubility of the additives in the oil to which they are to be added and the stability of the additive concentrates and their blends with other polymers employed as oil additives, such as, for example, EVA copolymers, are also improved.
The invention relates to copolymers containing
A) from 45 to 54 mol % of divalent structural units of the formula 1
in which a and b=0 or 1 and a+b=1,
B) from 35 to 53 mol % of divalent structural units of the formula 2
—H
2
C—CHR
2
— (2)
and
C) from 1 to 25 mol %, preferably from 1 to 20 mol %, of divalent structural units derived from polyolefins, where the polyolefins can be derived from monoolefins having 3 to 5 carbon atoms, wherein
a) R
1
is an alkyl or alkenyl radical having 10 to 40 carbon atoms or an alkoxyalkyl radical having 1 to 100 alkoxy units and 1 to 30 carbon atoms in the alkyl radical, and
b) R
2
is an alkyl radical having 10 to 50 carbon atoms,
c) the alkylvinylidene content of the polyolefins on whi
Krull Matthias
Nagel Waltraud
Clariant GmbH
Hanf Scott E.
Jackson Susan S.
Toomer Cephia D.
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